1. Field of the Invention
The present invention relates generally to data communications transceivers and more particularly to providing a standby mode in a communications system.
2. Background
A Universal Serial Bus (USB) is an open and freely licensed serial bus that supports 12 Mbps and up to 63 peripheral devices. It is designed to handle communication between a broad range of devices.
IEEE 1394b data bus is a complimentary technology with higher bandwidth than the Universal Serial Bus (USB), and is commonly used as a bridge between consumer products and computers. In particular, it is often used to link audio/video and data processing equipment to a personal computer. The IEEE 1394b standard defines a data transport bus that supports both asynchronous and isochronous data. The IEEE 1394b data bus includes two sub-layers: (1) a link layer; and (2) physical (PHY) layer, which transmits the encoded output of the link layer. IEEE 1394b data bus operates at a variety of speeds (100 Mbps, 200 Mbps, 400 Mbps, 800 Mbps) but is generally specified to run only up to 4.5 meters over copper cable. It provides a flexible interconnection that can usually be plugged into any vacant port. IEEE 1394b specification also provides a power saving standby mode of operation. Standby mode is a low energy consumption mode of operation for a port. If a node has only one active port, then the connection on this port can be placed into Standby. While in Standby mode, the node does not participate in normal bus activity. Other nodes on the bus of which the node is a member are not aware of any status change of the node.
IEEE 802 standards are a set of standards for LAN communications. IEEE 802.3 standard defines various protocols for transmitting data over 100 meters of unshielded twisted pair (UTP) at rates of 10 Mbps, 100 Mbps, and 1000 Mbps (1 Gbps) using 10BASE-T, 100BASE-TX, and 1000BASE-T respectively. The 802.3 standards include two sub-layers: (1) a Medium Access Control (MAC) layer; and (2) a Physical layer (PHY). The MAC layer includes specific methods for gaining access to the LAN.
Conventionally, 1000BASE-T uses a continuous signaling system. That is, if a 1000BASE-T device has no data to transmit or receive, the device transmits an IDLE code. Thus, unlike the 1394(b) standard, the IEEE 802.3 standard has no standby mode or low power mode. Therefore, in conventional 1000BASE-T, the power consumption while transmitting and receiving the IDLE code is similar to the power consumption while transmitting and receiving data.
Accordingly, what is needed is a method and system for providing a standby mode as a low energy consumption alternative to the conventional IDLE code that is currently used in the 1000BASE-T specification.